Eventmachine - Unable to load the Event Machine C Extension

I'm trying to run the current development version of Instiki on windows 8.1. I use ruby 2.4 . Bundle install succeeded. I also used the newest Nokogiri 1.8.0 version released some days ago that fixed a compatibility issuse with Ruby 2.4 on windows systems.

When I run instiki , It says that the system is unable to load the Event Machine C Extension.

In more detail : Unable to load Event Machine C extension: To use the pure ruby reactor use 'require'em/pure_ruby C:\instiki\vendor\rails\activesupport\lib\active_support\dependencies.rb:184: in 'require' cannot load such a file -- rubyeventmachine (missing source file)

If I understand this correctly , A file is missing which was required in some module so I might be able to circumvent this by including some other module that provides the same functionality which is "pure_ruby" . Is this right ? I tried to re-install this gem with no effect.